Process for preparing polyurethanes

ABSTRACT

The present invention relates to a new organic heterocyclic isocyanate which is the reaction product of an organic diisocyanate and an amino or hydroxy nitrile. The invention also relates to a process of producing such isocyanates by reacting an excess of the diisocyanate with the nitrile under conditions under which the nitrile will not decompose and then maintaining the reaction mixture at an elevated temperature until the isocyanate nitrile adduct cyclizes. The reaction may be carried out in the presence of a catalyst for isocyanate addition reactions. Additionally, the invention relates to a process for the production of polyurethane by the reaction of the heterocyclic isocyanates with compounds carrying at least two isocyanate reactive hydrogen atoms per molecule.

This is a division, of application Ser. No. 656,909 filed Feb. 10, 1976,now U.S. Pat. No. 4,173,567.

FIELD OF THE INVENTION

This invention relates to new organic isocyanates, to a process fortheir production and to their use as reactants for compounds containingisocyanate-reactive hydrogen atoms.

BACKGROUND OF THE INVENTION

German Offenlegungsschrift No. 2,329,300 relates to heterocyclicpolyisocyanates obtained by reacting diisocyanates with hydrocyanicacid. In addition to hydrocyanic acid, compounds which eliminatehydrocyanic acid, such as, for example, the addition products ofhydrocyanic acid with aldehydes or ketones (cyanhydrins), are alsorecommended as starting materials. The structure of the polyisocyanatesobtained by the process according to DT-OS No. 2,329,300 is independentof whether hydrocyanic acid or the above-mentioned hydrocyanic acidderivatives are used as starting material (Example 10 of DT-OS No.2,329,300). This discovery can be attributed to the fact that theauthors of DT-OS No. 2,329,300 used reaction conditions under which thehydrocyanic acid adducts with aldehydes or ketones decomposed into theirconstituents, hydrocyanic acid and aldehyde or ketone, before reactionwith the diisocyanate.

It has now surprisingly been found that new isocyanates havingadvantageous properties by comparison with the isocyanates of theabove-mentioned prior art can be obtained by carrying out the reactionbetween diisocyanate and cyanhydrins in a first reaction stage undersuch mild conditions that the cyanhydrin is not decomposed intohydrocyanic acid and carbonyl compound, but instead a simple adduct ofthe cyanhydrin with the diisocyanate is initially formed. The action ofheat on this intermediate product in the presence of excess quantitiesof starting diisocyanate results in the formation of new heterocyclicisocyanates corresponding to general formula (I) below (n=O, Y=--O--).These new isocyanates are distinguished from the isocyanates accordingto DT-OS No. 2,329,300 obtained from the corresponding startingmaterials in particular by their much lower viscosity and by the betterlacquer properties of the polyurethane lacquers produced from them.

According to the invention it has also been found that isocyanates whichare largely similar in structure and properties, and which, inparticular, have valuable lacquer properties, are formed from organicdiisocyanates by a similar reaction with α-aminonitriles, β-hydroxy orβ-aminonitriles.

SUMMARY OF THE INVENTION

Accordingly, the present invention relates to new isocyanatescorresponding to the formula: ##STR1##

The invention also relates to a process for the production of thecompounds of formula (I) wherein an organic diisocyanate correspondingto the formula:

    OCN--R--NCO                                                (II)

is reacted with a compound corresponding to the formula: ##STR2## toform an adduct corresponding to the formula: ##STR3## and the adductthus formed is subsequently converted into the required end product (I)by the heating in the presence of excess quantities of the diisocyanateof formula (II).

The invention also relates to the use of the preferred polyisocyanatesdescribed in more detail below, obtainable by the process according tothe invention, as reactants for compounds containing at least twoisocyanate-reactive hydrogen atoms in the production of polyurethaneplastics by the isocyanate polyaddition process known per se.

In the above formulae and hereinafter, R, R₁, R₂, X, Y, Z and n have thefollowing meanings:

R represents an aliphatic hydrocarbon radical having 2 to 12 carbonatoms, a cycloaliphatic hydrocarbon radical having 4 to 15 carbon atoms,an aromatic hydrocarbon radical having 6 to 15 carbon atoms or anaraliphatic hydrocarbon radical having 7 to 15 carbon atoms optionallysubstituted by halogen, C₁ -C₄ -alkyl, methoxy, nitro, and/or C₁ -C₄-carbalkoxy groups. R preferably represents an aliphatic hydrocarbonradical having 4 to 8 carbon atoms or a cycloaliphatic hydrocarbonradical having 5 to 10 carbon atoms.

R₁ and R₂ are the same or different and represent hydrogen an aliphatichydrocarbon radical having 1 to 17 carbon atoms, a cycloaliphatichydrocarbon radical having 4 to 15 carbon atoms, an aromatic hydrocarbonradical having 6 to 15 carbon atoms or an araliphatic hydrocarbonradical having 7 to 15 carbon atoms optionally substituted by halogen,C₁ -C₄ -alkyl, methoxy, nitro or C₁ -C₄ -carbalkoxy groups, or togetherwith the ring carbon atom form a cycloaliphatic ring having 4 to 8carbon atoms. R₁ and R₂ preferably represent an optionally olefinicallyunsaturated aliphatic hydrocarbon radical having 1 to 4 carbon atoms or,together with the ring carbon atom, a cycloaliphatic hydrocarbon radicalhaving 5 to 6 carbon atoms.

X represents hydrogen or --CO--NH--R--NCO. X preferably represents--CO--NH--R--NCO.

Y represents --O-- or --N(R₃)--, where R₃ is hydrogen, an aliphatichydrocarbon radical having 1 to 4 carbon atoms, a cycloaliphatichydrocarbon radical having 5 to 6 carbon atoms, a phenyl radical or--CO--NH--R--NCO. Y preferably represents --O--.

Z represents --O-- or a radical --N(R₄)--, where R₄ is hydrogen, analiphatic hydrocarbon radical having 1 to 4 carbon atoms or acycloaliphatic hydrocarbon radical having 5 to 6 carbon atoms or aphenyl radical. Z preferably represents --O--.

n=0 or 1, preferably 0.

DETAILED DESCRIPTION OF THE INVENTION

In the process according to the invention, diisocyanates of formula (II)are reacted with hydroxy or aminonitriles of formula (III) at atemperature in the range from about -25° C. to +200° C. and preferablyat a temperature in the range from about 0° C. to 180° C., preferably inthe presence of suitable catalysts. The process according to theinvention may be carried out, for example, by initially introducing thereactants in admixture and initiating the reaction by adding thecatalyst. However, it may also be carried out by initially introducingthe diisocyanate and catalyst, followed by addition of the hydroxy oraminonitrile. The process according to the invention probably passesthrough an intermediate stage of formula (IV) which is cyclized atelevated temperature into compounds of formula (I) (X=H, Y=--O-- or--N(R₄)--). If desired the diisocyanates or triisocyanates (I) accordingto the invention, in which X represents --CO--NH--R--NCO and Yrepresents --O-- or --N(R₃)-- (R₃ =--CO--NH--R--NCO), are then formed bya secondary reaction with excess diisocyanate (II) with the group ═NXwith the group --NR₄ -- (R₄ =H). Especially in cases where the α-hydroxynitriles, which represent particularly preferred starting compounds(III) for the process according to the invention, are used, it isimportant to ensure, by careful temperature treatment at the beginningof the reaction, that the addition reaction between (II) and (III) takesplace before the hydroxy nitrile (III) decomposes into its constituentsHCN and ##STR4## In practice, this result is achieved by carrying outthe primary reaction between (II) and (III) to form the intermediateproduct (IV) at a temperature in the range from about -25° C. to +80° C.and preferably at a temperature in the range from about +15° C. to +25°C. It is advisable to carry out the first step of the reaction at thesame temperature in those cases where α-aminonitriles are used asstarting materials. The temperature of the first reaction step is,however, less critical in the case where β-hydroxynitriles orβ-aminonitriles are used as starting materials. In these cases the firstreaction step can be carried out within above wide range from about -25°C. to +200° C. preferably from about 0° C. to 180° C. In ordersubsequently to cyclize the intermediate product (IV), the reactionmixture is then heated to elevated temperatures this means to about 40°to 160° C. preferably 60° to 120° C.

In general, from about 5 to 15 mols of diisocyanate (II) are preferablyused per mol of compound (III) in the process according to theinvention. The primary reaction between (III) and (II) to form (IV) isover when the heat effect observed when the reactants are combined withthe catalyst abates. The end of the cyclization reaction is indicated bythe disappearance of the nitrile edge in the infra red spectrum.

If desired, unreacted diisocyanate may be removed on completion of thereaction, for example, by thin-layer or rotary distillation or byextraction with solvents, for example, cyclohexane, hexane or petroleumether. However, the solutions of the new polyisocyanates in thediisocyanates used as starting compounds, obtainable in the processaccording to the invention, are also suitable for numerous applicationswhich are mentioned in more detail hereinafter. As already mentioned,the formation of diisocyanates corresponding to the above generalformula may be controlled by varying temperature. The formation oftriisocyanates is possible not only in cases where Y=--NH, but may alsobe obtained in cases where Y=--O-- by a secondary reaction, i.e. byreacting the excess diisocyanate used as starting material with thediisocyanate according to the invention (reaction of the diisocyanatewith the group --CO--NH--R--). In addition, heating the reaction mixtureto elevated temperatures for several hours results in the formation ofmixtures which, in addition to diisocyanates and triisocyanates, containhomologues of higher molecular weight. At elevated temperatures,polyisocyanates containing uretdione, biuret or isocyanurate groups canalso be expected to be formed in addition to the homologues of highermolecular weight. In the formation of these secondary products isundesirable, it is advisable to carry out the process according to theinvention at low temperatures in the range from about 0° C. to 80° C.,in which case the reaction mixture is heated to this temperature forabout 30 to 120 minutes. monoisocyanates are formed if the reactiontemperature is kept below 80° C. Above secondary reaction leading to di-and triisocyanates take place at temperatures of above 80° C. as e.g.80°-200° C. The degree of diisocyanate and/or triisocyanate formation bysaid secondary reactions can be determined by controlling theNCO-content of the reaction mixture.

Providing these precautionary measures are taken, removal of the excessstarting diisocyanate leaves and products of which at least about 70%and preferably at least about 90% consist of the mono-, di- andtri-isocyanates corresponding to general formula (I) above.

The catalysts used, which are mentioned hereinafter, may generallyremain in the reaction products without any adverse effect upon thestability of the end products in storage. In cases where the catalystsused in accordance with the invention are harmful in the production ofplant protection agents, PU-plastics, PU-lacquers and PU-films, they areremoved by filtration, centrifuging or decanting (insoluble catalysts)or are deactivated by alkylation, acylation or salt formation.

Any organic diisocyanates corresponding to the general formula R(NCO)₂,where R is as defined above, may be used in the process according to theinvention. Preferred aliphatic or cycloaliphatic diisocyanates are, forexample, tetramethylene diisocyanate, pentamethylene diisocyanate,hexamethylene diisocyanate, 1,3-cyclopentylene diisocyanate,1,4-cyclohexylene diisocyanate, 1,2-cyclohexylene diisocyanate,hexahydroxylylene diisocyanate, 4,4'-dicyclohexyl diisocyanate,1,2-di-(isocyanatomethyl)-cyclobutane,1,3-bis-(isocyanatopropyl)-2-methyl-2-propyl propane,1-methyl-2,4-diisocyanatocyclohexane, 1-methyl-2,6-diisocyanatocyclohexane, bis-(4-isocyanatocyclohexyl)-methane,1,4-diisocyanatocyclohexane and 1,3-diisocyanatocyclohexane or3,3,5-trimethyl-5-isocyanatomethyl cyclohexyl isocyanate ("isophoronediisocyanate"). In addition to aliphatic and cycloaliphaticdiisocyanates of this kind, it is also possible in the process accordingto the invention to use aromatic diisocyanates such as, for example,2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene or4,4'-diisocyanatodiphenyl methane, araliphatic diisocyanates, such as m-or p-xylylene diisocyanate, or diisocyanates containing ester groupssuch as 2,6-diisocyanato caproic acid esters, β-isocyanatoethyl estersand γ-isocyanatopropyl esters of isocyanato caproic acid.

Hydroxy and aminonitriles (III) suitable for use in the processaccording to the invention are the following:

(1) α-hydroxy nitriles such as, for example, the cyanhydrins offormaldehyde, acetaldehyde, propionaldehyde, butyraldehyde,isobutyraldehyde, acetone, methylethyl ketone, isopropyl methyl ketone,monochloracetone, benzaldehyde, o-nitrobenzaldehyde,m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-chlorobenzaldehyde,m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-methoxy benzaldehyde,p-methoxy benzaldehyde, m-methyl benzaldehyde, p-methyl benzaldehyde,benzyl methyl ketone, β-phenyl ethyl ketone, β-phenyl propyl ketone,cyclopentanone, cyclohexanone, isopropyl phenyl ketone, cyclohexylphenyl ketone, 2-methyl cyclohexanone, 3-methyl cyclohexanone, 4-methylcyclohexanone, cycloheptanone, chloral, acrolein, crotonaldehyde andacetoacetic acid ethyl ester.

(2) α-aminonitriles such as, for example, α-aminoacetonitrile,α-aminopropionitrile, α-amino-α-methyl propionitrile, α-(N-methylamino)-propionitrile, α-aminobutyronitrile, α-aminoisobutyronitrile,α-amino-α-methyl propionic acid nitrile, α-amino-α-methylisobutyronitrile, α-methyl aminoisobutyronitrile, α-butylaminoisobutyronitrile, α-cyclohexyl aminoisobutyronitrile, α-phenylaminoisobutyronitrile, α-1-cyclohexyl amino-1-cyanocyclohexane and(α-amino-α-phenyl acetic acid nitrile).

(3) β-hydroxy nitriles such as, for example, β-hydroxy propionitrile,β-hydroxy-α-methyl propionitrile, β-hydroxy-β-methyl propionitrile,β-hydroxy-β-cyclohexyl propionitrile and β-hydroxy-β-phenylpropionitrile.

(4) β-aminonitriles such as, for example, β-aminopropionitrile, β-methylaminopropionitrile, β-hexyl aminopropionitrile, β-cyclohexylaminopropionitrile, β-amino-α-methyl propionitrile and β-methylamino-β-methyl propionitrile.

It is, of course, also possible in the process according to theinvention to use any mixtures of the compounds (III) mentioned by way ofexample in (1) to (4) above, more especially for controlling the serviceproperties of the end products. The cyanhydrins of the unsubstitutedaliphatic or cycloaliphatic aldehydes or ketones mentioned in (1) aboveare particularly preferred for the process according to the invention.

Compounds accelerating the isocyanate polyaddition reaction, known perse from polyurethane chemistry, are used as catalysts in the processaccording to the invention. Compounds of this kind are, in particular,tertiary amines such as, for example, triethyl amine,diaza-bicyclo-(2,2,2)-octane, 1,5-diaza-bicyclo-(4,3,0)-non-5-ene,1,8-diaza-bicyclo-(5,4,0)-undec-7-ene, dimethyl aniline, dimethyl benzylamine, pyridine, 2-, 3-, 4-picoline, N,N-diethyl aniline, quinoline,N-methyl piperidine, N-methyl dicyclohexyl amine, N,N-dimethylcyclohexyl amine, N-cyclohexyl piperidine, N-cyclohexyl morpholine and2,6-, 2,4-lutidine; organic zinc compounds, such as, for example, thoseof 2-ethyl caproic acid, organic tin compounds such as, for example,dibutyl tin dilaurate, bis-(tributyl tin)-oxide, dibutyltin-bis-(2-ethyl hexoate) or tetrabutyl tin. Other suitable catalystsare lead compounds, such as, trimethyl lead acetate or N-(tri-n-butyllead)-imidazole or phosphorus compounds, such as, triphenyl phosphine ortributyl phosphine, and basic salts of hydrocyanic acid, such as sodiumcyanide or potassium cyanide. The catalysts mentioned by way of exampleare used in quantities of from about 0.01 to 3 mol % and preferably inquantities of from about 0.05 to 1 mol %, based on compound (III), inthe process according to the invention. Further suitable catalysts aredisclosed in Polyurethanes: Chemistry and Technology, Part I, bySaunders and Frisch, Interscience Publishers, 1964.

The process according to the invention may be carried out either in theabsence or even in the presence of an inert organic solvent. Suitableinert solvents are, for example, aliphatic and cycloaliphatichydrocarbons, halogencontaining hydrocarbons such as methylene chloride,chloroform, di- and tri-chlorethylene, aromatic hydrocarbons, such asbenzene, toluene, xylene, halogenated aromatic hydrocarbons such aschlorobenzene, dichlorobenzene, and trichlorobenzene, dioxane, ethylacetate, ethyl glycol acetate, acetone, acetonitrile, dimethyl formamideand mixtures of these solvents.

The polyisocyanates (I) according to the invention represent a new classof organic polyisocyanates. The fact that they are compounds having thegeneral structure indicated above is apparent from molecular weightdetermination and from infrared (Makromol. Chem. 78, 191 (1964), nuclearresonance and mass spectroscopic data. The new compounds are suitablefor use as intermediate products in the production of plant-protectionagents and in particular represent valuable starting materials for theproduction of polyurethane plastics. In particular, the polyisocyanatesaccording to the invention having aliphatically bound isocyanate groupsare valuable starting materials for the production of light-stablepolyurethane lacquers and films. The new polyisocyanates are readilysoluble in conventional lacquer solvents and are highly compatible withpigments. They are particularly suitable for low-solvent lacquer systemsowing to their low viscosity. Their greatly reduced vapor pressure bycomparison with the corresponding diisocyanates used as startingmaterials, and their resulting physiological acceptability, are ofconsiderable practical significance.

EXAMPLE 1

2016 g of hexamethylene diisocyanate (12 mols) and 1 ml of triethylamine are initially introduced into a three-necked flask, followed bythe dropwise addition over a period of 30 minutes at room temperature of68.4 g of glycol nitrile (1.2 mols). The mixture is then slowly heatedto 160° C. and, after 10 minutes at that temperature, is cooled to roomtemperature. The catalyst is destroyed by means of benzoyl chloride andthe reaction product freed from excess hexamethyl diisocyanate bythin-layer distillation.

Yield: 530 g of a diisocyanate having the following idealized structure:##STR5##

NCO found: 21.3%

NCO calculated: 21.4%

η₂₅° C.: 440 cP

Analysis: calculated: C 54.95, H 6.92, N 17.80, O 20.33. found: C 55.1,H 7.00, N 18.1, O 20.3.

EXAMPLE 2

2523 g of hexamethylene diisocyanate (15 mols) are reacted with 157 g ofisobutyraldehyde cyanhydrin (1.5 mols) in the presence of 2 g ofdiaza-bicyclo-(2,2,2)-octane in the same way as in Example 1. Removal ofthe excess hexamethylene diisocyanate by extraction with cyclohexaneleaves 772 g of a diisocyanate having the following idealized structure:##STR6##

η₂₅° C.: 2080 cP

NCO calculated: 19.3%

NCO found: 19.1%

Analysis: calculated: C 57.91, H 7.64, N 16.08, O 18.37. found: C 57.8,H 7.7, N 16.3, O 13.3.

EXAMPLE 3

53 g (0.5 mol) of benzaldehyde (freshly distilled) and 0.5 ml oftriethylamine are combined in a stirrer-equipped vessel and 20 ml ofhydrocyanic acid (0.5 mol) added dropwise at such a rate that thetemperature does not exceed 40° C. After stirring for 60 minutes at roomtemperature, 841 g of hexamethylene diisocyanate (5 mols) and 0.5 ml ofthe zinc(II)salt of 2-ethyl caproic acid are added. The furtherprocedure is then as described in Example 1.

Removal of the monomer leaves 180 g of a diisocyanate having thefollowing idealized structure: ##STR7##

η₂₅° C.: 1050 cP

NCO found: 17.5%

NCO calculated: 17.92%

Analysis: calculated: C 61.39, H 6.66, N 14.92, O 17.04. found: C 60.9,H 6.5, N 14.9, O 17.0.

EXAMPLE 4

841 g of hexamethylene diisocyanate (5 mols) are reacted with 41.5 g ofacrolein cyanhydrin (0.5 mol) in the presence of 0.5 ml of quinoline and1 g of pyrocatechol in the same way as in Example 1. The reactionmixture obtained is subject to thin-layer distillation twice at 180° C.in an oil pump vacuum.

Yield: 190 g of a diisocyanate having the following idealized structure:##STR8##

η₂₅° C.: 715 cP

NCO calculated: 20.0%

NCO found: 19.9%

Analysis: calculated: C 57.26, H 6.97, N 16.70, O 19.07. found: C 57.2,H 7.2, N 16.7, O 19.3.

EXAMPLE 5

3360 g of hexamethylene diisocyanate (20 mols), 186.9 g of cyclohexanonecyanhydrin (1.5 mols), 1 ml of tin octoate and 1 ml of triethyl amine,are reacted as described in Example 1. Removal of the monomer leaves 782g of a polyisocyanate having the following idealized structure: ##STR9##

η₂₅° C.: 1770 cP

NCO calculated: 18.2%

NCO found: 17.9%

Analysis: calculated: C 59.85, H 7.64, N 15.17, O 17.33. found: C 59.8,H 7.8, N 15.4, O 17.3.

EXAMPLE 6

3364 g of hexamethylene diisocyanate (20 mols) and 2 mols ofacetaldehyde cyanhydrin (142 g) are mixed under nitrogen in a 5 litercapacity stirrer-equipped apparatus. Following the addition of 1 ml ofzinc octoate, a weakly exothermic reaction begins, being over after 30minutes. Following the addition of 1 ml of triethyl amine, the mixtureis stirred for 15 minutes at room temperature, quickly heated to 160° C.and kept at that temperature for 15 minutes. The reaction mixture isfreed from excess hexamethylene diisocyanate by thin-layer distillation.

Yield: 952 g of a polyisocyanate having the following idealizedstructure: ##STR10##

η₂₅° C.: 480 cP

NCO calculated: 20.6%

NCO found: 20.3%

Analysis: calculated: C 56.0, H 7.17, N 17.09, O 19.63. found: C 55.8, H7.3, N 17.0, O 20.0.

EXAMPLE 7

2523 g of hexamethylene diisocyanate (15 mols) and 127 g ofpropionaldehyde cyanhydrin are reacted in the presence of 1 ml of zincoctoate and 1 ml of triethylamine in the same way as described inExample 6.

Yield: 821 g of polyisocyanate having the following idealized structure:##STR11##

η₂₅° C.: 720 cP

NCO calculated: 19.95%

NCO found: 19.7%

Analysis: calculated: C 56.99, H 7.41, N 16.62, O 18.98. found: C 56.7,H 7.2, N 16.8, O 19.0.

EXAMPLE 8

841 g of hexamethylene diisocyanate (5 mols) are mixed at roomtemperature with 78.5 g of acetoacetic ester cyanhydrin (0.5 mol), 0.5ml of zinc octoate and 0.5 ml of triethylamine in a stirrer-equippedvessel. The mixture is then heated for 10 minutes to 160° C. and thecatalyst neutralized with 0.5 ml of acetyl chloride. The reactionproduct is subjected to thin-layer distillation twice at 180° C. in anoil pump vacuum and all but 0.1% of the monomer, (hexamethylenediisocyanate), removed.

Yield: 195 g of a polyisocyanate having the following idealizedstructure: ##STR12##

η₂₅° C.: 5200 cP

NCO calculated: 17.05%

NCO found: 16.8%

Analysis: calculated: C 55.97, H 7.15, N 14.19, O 22.69. found: C 55.7,H 6.93, N 14.5, O 22.8.

EXAMPLE 9

42.5 g of acetone cyanhydrin (0.5 mol) and 0.5 g ofdiazabicyclo-(2,2,2)-octane are added to 1250 g of4,4'-di-isocyanatodiphenyl methane (5 mols), followed by heating for 60minutes to 160° C. After 30 minutes at that temperature, the reactionmixture is left to cool. 1240 g of a polyisocyanate having the followingidealized structure: ##STR13## in 3 mols of 4,4'-diisocyanatodiphenylmethane are obtained. The monomer-free polyisocyanate may be freed fromthe monomer by extraction.

NCO calculated: 14.86%

NCO found: 14.5%

Analysis: calculated: C 69.73, H 4.65, N 11.96, O 13.66. found: C 69.5,H 4.4, N 12.1, O 13.8.

EXAMPLE 10

870 g of 2,4-diisocyanatotoluene (5 mols) are combined while stirring ina reaction vessel with 0.5 g of 1,5-diazabicyclo-(4,3,0)-non-5-ene, 0.5g of dibutyl tin dilaurate and 42.5 g of acetone cyanhydrin (0.5 mol),followed by heating for 2 hours to 150° C. After another 30 minutes, thereaction mixture is left to cool and, providing the reaction mixture isnot directly used for further reactions, is extracted with cyclohexaneuntil the monomer has been removed. 285 g of a polyisocyanate having thefollowing idealized structure: ##STR14## in the form of a white solidmelting at approximately 195° C. are obtained.

NCO calculated: 19.4%

NCO found: 19.1%

Analysis: calculated: C 60.96, H 4.42, N 16.16, O 18.46. found: C 60.7,H 4.6, N 16.3, O 18.2.

EXAMPLE 11

841 g of hexamethylene diisocyanate (5 mols), 50 g of methyl ethylketone cyanhydrin, 0.5 g of triethylamine and 0.5 ml of zinc octoate arereacted in the same way as described in Example 1. On cooling, thetriethylamine is blocked by the addition of 0.6 g of p-toluene sulphonicacid chloride.

The mixture is introduced cold into the thin-layer distillationapparatus in which it is subjected to thin-layer distillation at 180° to185° C./0.05 Torr (oil pump).

Yield: 218 g of a polyisocyanate having the following idealizedstructure: ##STR15##

η₂₅° C.: 3200 cP

NCO calculated: 19.3%

NCO found: 19.5%

Analysis: calculated: C 57.91, H 7.64, N 16.08, O 18.34. found: C 58.2,H 7.81, N 15.9, O 18.1.

EXAMPLE 12

In a stirrer-equipped apparatus, 20 ml of hydrocyanic acid (0.5 mol) areadded to 85 g (0.5 mol) of undecanone-(2) in the presence of 0.5 ml oftriethylamine, followed by stirring for 30 minutes at 40° C. 841 g ofhexamethylene diisocyanate (5 mols) and 0.5 ml of tin octoate areintroduced into the cooled mixture. After heating for 60 minutes to 160°C., the mixture is stirred for 30 minutes at that temperature. Aftercooling, a polyisocyanate having the following idealized structure canbe isolated by thin layer distillation in a yield of 293 g: ##STR16##

η₂₅° C.: 3650 cP

NCO calculated: 15.75%

NCO found: 16.1%

Analysis: calculated: C 63.01, H 8.88, N 13.12, O 14.99. found: C 63.2,H 8.91, N 13.1, O 14.7.

EXAMPLE 13

Following the procedure described in Example 1, 3364 g of hexamethylenediisocyanate (20 mols) and 170 g of acetone cyanhydrin (2 mols) aremixed with catalytic quantities of zinc octoate and triethylamine and,after the exothermic reaction has abated, the reaction mixture is heatedto 160° C. and kept at that temperature for 10 minutes. The cooledreaction mixture can be obtained free from monomer by countercurrentextraction in a column with cyclohexane or petroleum ether.

Yield: 1042 g of a polyisocyanate having the following idealizedstructure: ##STR17##

η₂₅° C.: 1720 cP

NCO calculated: 19.9%

NCO found: 19.6%

Analysis: calculated: C 56.99, H 7.41, N 16.62, O 18.98. found: C 57.1,H 7.12, N 16.9, O 18.7.

EXAMPLE 14

Following the procedure of Example 1, 222 g of isophorone diisocyanate(1 mol), 8.5 g of acetone cyanhydrin (0.1 mol), 0.1 mol of zinc octoateand 0.1 ml of triethylamine are heated for 1 hour to 160° C. andsubsequently subjected to thin-layer distillation at 180° C./0.2 Torr.47 g of a resin-like polyisocyanate having the following idealizedstructure are obtained: ##STR18##

NCO calculated: 15.9%

NCO found: 15.7%

Analysis: calculated: C 63.49, H 8.18, N 13.22, O 15.10. found: C 63.2,H 8.0, N 13.4, O 15.3.

EXAMPLE 15

673 g of hexamethylene diisocyanate (4 mols) and 174 g of2,4-diisocyanatotoluene (1 mol) are reacted with 42.5 g of acetonecyanhydrin (0.5 mol) in the presence of 0.5 ml of triethylamine. Afterthe weakly exothermic reaction has abated, the reaction mixture isheated for 1 hour to 160° C. A clear, low-viscosity reaction product isobtained after cooling and may be freed from the monomer by extractionwith ether. The monomer-free polyisocyanate has the following idealizedstructure: ##STR19##

NCO calculated: 19.65%

NCO found: 19.3%

Analysis: calculated: C 59.0, H 5.90, N 16.39, O 18.72. found: C 58.8, H5.81, N 16.40, O 18.8.

EXAMPLE 16

841 g of hexamethylene diisocyanate (5 mols) are reacted with 42.5 g ofacetone cyanhydrin (0.5 mol) in the presence of 0.2 ml of triethylamineand 0.2 ml of zinc octoate by stirring the reaction mixture for 3 hoursat 70° C. The unreacted hexamethylene diisocyanate is then removed fromthe reaction product by extraction with petroleum ether. 130 g of areaction product essentially consisting of a monoisocyanate having thefollowing idealized structure are obtained: ##STR20##

NCO calculated: 16.6%

NCO found: 16.9%

Analysis: calculated: C 56.90, H 7.56, N 16.59, O 18.95. found: C 57.0,H 7.71, N 16.3, O 18.8.

EXAMPLE 17

In a stirrer-equipped apparatus, 336 g of hexamethylene diisocyanate (2mols) are reacted for 2 hours at 40° C. with 21.3 g of acetaldehydecyanhydrin (0.3 mol). 0.1 g of diaza-bicyclo-(2,2,2)-octane and 0.01 gof tin octoate are used as catalyst. The reaction product is obtainedfree from monomer by extraction with cyclohexane/petroleum ether. 75 gof a reaction product essentially consisting of a monoisocyanate havingthe following idealized structure are obtained: ##STR21##

NCO calculated: 17.6%

NCO found: 17.9%

Analysis: calculated: C 55.21, H 7.16, N 17.56, O 20.06. found: C 55.30,H 7.42, N 17.3, O 19.7.

EXAMPLE 18

To prepare a lacquer, 154 parts by weight of a polyester, prepared fromphthalic acid anhydride and trimethylol propane, OH-number 260, in theform of a 65% solution in ethyl glycol acetate, 8.40 parts by weight ofzinc octoate (8% of Zn) in the form of a 10% solution in xylene, 105.30parts by weight of titanium dioxide and 141.80 parts by weight of ethylglycol acetate, are mixed with 110.50 parts by weight of thepolyisocyanate of Example 5.

The mixture has a viscosity of about 25 seconds, as determined in a 4 mmDIN cup (DIN 53 211). This viscosity makes the mixture suitable forspraying, although it may be adjusted to the required level by adding,or reducing the quantity of, ethyl glycol acetate. This lacquer mixturehas a processing time of 2 hours. Properties of the lacquer film: 7.5 mmErichsen indentation DIN 53 156, pendulum hardness (according to Konig)DIN 53 157, 218 seconds. The lacquer is dried for 30 minutes at 120° C.

EXAMPLE 19

To prepare a lacquer, 154 parts by weight of a 65% solution of apolyester prepared from phthalic acid and trimethylol propane (8% OH) inethyl glycol acetate, 8 parts by weight of zinc octoate (8% of Zn) inthe form of a 10% solution in xylene, 100.1 parts by weight of titaniumdioxide and 119.8 parts of ethyl glycol acetate, are mixed with 100.1parts by weight of the polyisocyanate of Example 6.

The lacquer thus prepared has a viscosity of 25 seconds, as measured ina 4 mm DIN cup (DIN 53 211), for a solids content of 62.3%. Theviscosity may be adjusted by the quantity of ethyl glycol acetate usedfor roll coating, two-component hot spraying or for conventionalspread-coating and spray-coating techniques. The lacquer has aprocessing time of about 5 hours. The lacquer is dried for up to 30minutes at 120° C.

Properties of the lacquer film:

Erichsen indentation DIN 53 156 8 mm

pendulum hardness (according to Konig) DIN 53 157 - 210 seconds.

EXAMPLE 20

In a 1.5 liter capacity stirrer-equipped apparatus, 1682 g ofhexamethylene diisocyanate (10 mols) and 84 g of α-aminoisobutyronitrile(1 mol) are slowly heated to 160° C. in the presence of 1 ml oftriethylamine. After stirring for 10 minutes at that temperature, theexcess hexamethylene diisocyanate is removed by thin-layer distillationat 180° C./0.2 Torr.

577 g of a polyisocyanate having the following idealized structure areobtained: ##STR22##

η₂₅° C. : 11,320 cP

NCO calculated: 21.4%, found: 21.6%.

EXAMPLE 21

2523 g of hexamethylene diisocyanate (15 mols) and 126 g ofα-aminoisobutyronitrile (1.5 mols) are reacted with one another in thesame way as described in Example 20, but in the absence of a catalyst.Thin-layer distillation gives 603 g of a reaction product having thefollowing idealized structure: ##STR23##

η₂₅° C..: 5850 cP

NCO calculated: 20.0%, found: 20.1%

EXAMPLE 22

98 g of β-methyl aminoisobutyronitrile (1 mol) are added dropwise at 40°C. to 1680 g of hexamethylene diisocyanate (10 mols). After theexothermic reaction has abated, the reaction mixture is briefly heatedto 160° C. and, after cooling, is subjected to thin-layer distillationat 180° C./0.2 Torr in order to remove the monomeric hexamethylenediisocyanate. 430 g of a polyisocyanate having the following idealizedstructure are obtained: ##STR24##

η₂₅° C. : 15,400 cP

NCO calculated: 19.3%, found: 18.8%

EXAMPLE 23

11.2 g of α-ethyl aminoisobutyronitrile (0.1 mol), containing 0.1 ml oftriethylamine and 0.1 ml of zinc octoate, are added dropwise at roomtemperature to 168 g of hexamethylene diisocyanate (1 mol). After theexothermic reaction has abated, the mixture is briefly heated to 140° C.and subsequently subjected to thin-layer distillation at 170° C./0.1Torr. 41 g of polyisocyanate having the following idealized structureare obtained: ##STR25##

η₂₅° C. : 21,200 cP

NCO calculated: 18.7%, found: 18.4%.

EXAMPLE 24

840 g of hexamethylene diisocyanate (5 mols) and 62 g of1-amino-1-cyanocyclohexane are reacted in the same way as described inExample 21 and the reaction product freed from the excess monomer bythin-layer distillation. 218 g of a polyisocyanate having the followingidealized structure are obtained: ##STR26##

η₂₅° C. : 16,700 cP

NCO calculated: 18.2%, found: 18.4%.

EXAMPLE 25

840 g of hexamethylene diisocyanate (5 mols) and 69 g of 1-methylamino-1-cyanocyclohexane (0.5 mol) are mixed and, after the exothermicreaction has abated, briefly heated to 150° C. After cooling, the excesshexamethylene diisocyanate is removed by repeated extraction withcyclohexane. 225 g of a polyisocyanate having the following idealizedstructure are obtained: ##STR27##

η₂₅° C. : 25,000 cP

NCO calculated: 17.7%, found: 17.3%.

EXAMPLE 26

0.1 ml of triethylamine and 0.1 ml of zinc octoate are added to 840 g ofhexamethylene diisocyanate (5 mols), followed by the gradual dropwiseaddition at room temperature 103 g of 1-cyclohexylamino-1-cyanocyclohexane (0.5 mol). After the exothermic reaction hasabated, the reaction mixture is heated for 10 minutes to 160° C.,followed by the addition of 0.5 ml of benzoyl chloride. After cooling,the reaction product is extracted with cyclohexane and petroleum ether.253 g of a polyisocyanate having the following idealized structure areobtained: ##STR28##

η₂₅° C. : 34,000 cP

NCO calculated: 15.5%, found: 16.0%.

EXAMPLE 27

1680 g of hexamethylene diisocyanate (10 mols) are introduced into a 3liter capacity three-necked flask, followed by the dropwise additionover a period of 30 minutes of 84 g of 3-methyl aminopropionitrile. Theinternal temperature rises to 52° C. After the exothermic reaction hasabated, 1 g of diazabicyclooctane and 1 ml of zinc octoate areintroduced into the reaction mixture, followed by heating for 1 hour to160° C. Removal of the monomeric hexamethylene diisocyanate bythin-layer distillation gives 380 g of a polyisocyanate having thefollowing idealized structure: ##STR29##

η₂₅° C. : 1950 cP

NCO calculated: 20%, found: 19.6%.

EXAMPLE 28

841 g of hexamethylene diisocyanate (5 mols) are reacted with 35.5 g ofβ-aminopropionitrile (0.5 mol) in the same way as described in Example27. 329 g of a polyisocyanate having the following idealized structureare obtained by way of the urea stage: ##STR30##

η₂₅° C. : 3852 cP

NCO calculated: 20.7%, found: 20.4%.

EXAMPLE 29

504 g of hexamethylene diisocyanate (3 mols) are reacted with 46.8 g ofN-cyanoethyl aminoacetic acid ethyl ester (0.3 mol) in the same way asdescribed in Example 27. Before thin-layer distillation, the catalystsare blocked by the addition of 0.5 ml of acetyl chloride. 150 g of apolyisocyanate having the following idealized structure are obtained.##STR31##

η₂₅° C. : 460 cP

NCO calculated: 17.6%, found: 17.4%.

It is to be understood that any of the components and conditionsmentioned as suitable herein can be substituted for its counterpart inthe foregoing examples and that although the invention has beendescribed in considerable detail in the foregoing, such detail is solelyfor the purpose of illustration. Variations can be made in the inventionby those skilled in the art without departing from the spirit and scopeof the invention except as it may be limited by the claims.

What is claimed is:
 1. A process for the production of polyurethanes orof polyurethane lacquers comprisingreacting a compound containing atleast two isocyanate-reactive hydrogen atoms with an organicdiisocyanate of the formula ##STR32## in which R represents asubstituted or unsubstituted aliphatic hydrocarbon group having 2 to 12carbon atoms, a substituted or unsubstituted cycloaliphatic hydrocarbongroup having 4 to 15 carbon atoms, a substituted or unsubstitutedaromatic hydrocarbon group having 6 to 15 carbon atoms or a substitutedor unsubstituted araliphatic hydrocarbon group having 7 to 15 carbonatoms, said hydrocarbon group having at most three substituents selectedfrom the group consisting of halogen, C₁ -C₄ --alkyl, methoxy, nitro andC₁ -C₄ -carbalkoxy groups, represents --O-- or --N(R₃)--, where R₃represents hydrogen, an aliphatic hydrocarbon group having 1 to 4 carbonatoms, a cycloaliphatic hydrocarbon group having 5 to 6 carbon atoms, aphenyl group or --CO--NH--R--NCO, n=0 or 1, R₁ and R₂ are the same ordifferent and represent hydrogen, a substituted or unsubstitutedaliphatic hydrocarbon group having 1 to 17 carbon atoms, a substitutedor unsubstituted cycloaliphatic hydrocarbon group having 4 to 15 carbonatoms, a substituted or unsubstituted aromatic hydrocarbon group having6 to 15 carbon atoms or a substituted or unsubstituted araliphatichydrocarbon group having 7 to 15 carbon atoms, said hydrocarbon grouphaving at most three substituents selected from the group consisting ofhalogen, C₁ -C₄ -alkyl, methoxy, nitro and C₁ -C₄ -carbalkoxy groups orR₁ or R₂ together with the ring carbon atom form a cycloaliphatic ringhaving 4 to 15 carbon atoms, and represents --CO--NH--R--NCO.
 2. Theprocess according to claim 1 wherein the compound containing at leasttwo isocyanate-reactive hydrogen atoms is a hydroxy polyester.
 3. Theprocess for the production of polyurethane lacquers according to claims1 or 2 wherein the reaction is carried out in the presence of an inertorganic solvent.
 4. The process according to claims 1 or 2 whereinpigmenting agents are added during the production of the polyurethanelacquers.